I wouldn't worry about the 4/5 AM + ABarr trick very much. That's just a simple trick to try and squeeze out every inch of possible DPS boost. The other two specs may not have something as tricky as that, but by not using this method does not mean you are not able to do high DPS. It's basically splitting hairs between doing 3300 DPS on a raid boss or doing 3400 DPS (just a simple example). It may not be obvious here, but it also makes the arcane yet even worse on mana longevity, meaning that you are going to run out of mana even faster (bad if everyone else is not pumping out similar DPS). 95% of the time, I just use the macro I posted above and still do great DPS.

I didn't have mana issues too much with a 2 min evocation cooldown plus using my mana gems when they were available in 10-man Naxx, until I got to Kel'Thuzad. With all the initial trash and a 5mil hp boss fight, I started getting crunched for mana already when he was about 40%. I actually went back to just using my macro around this time to start slowing my mana consumption. Didn't matter much though anyways since our offtank died and one of the adds came over and wtfpwnd me around 25% before I realized what happened and we got them under control again. Ended up third in total damage on KT even after the end of the fight and missing a quarter of it.